2007 Fiscal Year Final Research Report Summary
PROPERTY DEVELOPMENT OF NOVEL ENDOHEDRAL FULLERENES THROUGH SYNTHETIC RESEARCH
| Project/Area Number |
18550033
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Organic chemistry
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| Research Institution | Fukui University of Technology |
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Principal Investigator |
KOMATSU Koichi Fukui University of Technology, DEPARTMENT OF ENGINEERING, PROFESSOR (70026243)
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| Co-Investigator(Kenkyū-buntansha) |
MURATA Yasujiro KYOTO UNIVERSITY, INSTITUTE FOR CHEMICAL RESEARCH, ASSOCIATE PROFESSOR (40314273)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Endohedral Fullerene / Superconductivity / Spin-lattice Relaxation / Excited Singlet Oxygen / Open-cage Fullerene / Molecular Hydrogen / Selenium / Nitroxide Radical |
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| Research Abstract |
We have established the molecular surgical method for the creation of endohedral fullerenes, which were obtained only in minute amounts according to the conventional physical procedures. The present research aims at the development of new properties in this kind of new endohedral fullerenes.
1. Endohedral fullerenes encapsulating hydrogen and also deuterium, H2@C60 and D2@C60, were newly synthesized according to the molecular surgical method.
2. An endohedral fullerene doped with potassium, K3/H2@C60, was prepared and it was shown to become an electric superconducter below the critical temperature of Tc=19.2K. This is the same temperature observed for empty C60, indicating the absence of any electronic interaction between encapsulated hydrogen and the fullerene cage under the K-doped conditions.
3. The bimolecular contribution to the spin-lattice relaxation rate for the protons of H2 and H2@C60 dissolved in various organic solvents was measured in the presence of paramagnetic nitroxide ra
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dicals. It was found that the relaxation effect of the paramagnets is enhanced five-fold in H2@C60 compared to H2 under the same conditions.
4. The quenching of singlet molecular oxygen ^1O2 by C60, H2@C60, and D2@C60 was examined and compared with that by free H2 and D2 in solution. The rate constants for quenching of ^1O2 by H2@C60 and D2@C60 were found to be larger than those for the quenching of ^1O2 by H2 and D2. This indicates that the presence of a pi-conjugated C60 cage plays an important role for the, ^1O2 quenching.
5. Open-cage fullerenes incorporating a He atom and a H2 molecule were synthesized. The ^1H NMR chemical shift of a proton attached outside the cage is influenced by the inside guest species, thus indicating the presence of some interaction between the guest species and the open-cage fullerene cage.
6. An open-cage fullerene having a selenium atom instead of sulfur at the rim of a 13-membered-ring orifice was newly synthesized. The encapsulation and release of a hydrogen molecule were examined, and it was found that activation of these processes is smaller indicating that the orifice size has been enlarged by introduction of the selenium atom. Less
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